Environmental influence in cyathostominae ecology

Studies of the survival, recovery and migration of cyathostomin infective larvae in a Bermuda grass (Cynodon dactylon) pasture were carried out in the Baixada Fluminense county, Rio de Janeiro state. Fresh feces (+/-1 kg) from naturally infected horses were deposited monthly on Bermuda grass. Samples of feces and surrounding grass were collected every seven days, from March 2005 to March 2007, and larvae were counted. In the feces, cyathostomin L3 survived for up to 15 weeks, with higher recovery rates during the rainy period (46,228/kg dried herbage - dh), and on the grass for up to 12 weeks. The recovery of L3 was greater during the dry period in the grass base (1,868/kg dh) compared to the apex (809/kg dh). The migration of L3 from feces to grass varied during the period. Climatic factors, such as temperature and rain, influenced the development and migratory behavior of cyathostomin L3. With regard to the grass base, significant differences were observed at the different collection times. The results demonstrate that under local conditions animals are at permanent risk since the infective larvae are always present on pasture.